Ted Chiang(click on names to see more mathematical fiction
by the same author)

...

Contributed by
"William E. Emba"

"An experimental treatment for a drowning victim turns him into
an incredible supergenius. Mathematics is mentioned several
times in passing, and twice the supergenius explicitly uses it
for his applications. But he forgets one obvious thing."

Originally published in Isaac Asimov's Science Fiction Magazine, August
1991.

Contributed by
Lapo Fanciullo

This novelette is breathtaking - perhaps the only serious attempt I've ever read at describing what a superhuman mind could be - but its focus on finding patterns and meaning in the world makes little mention of explicit mathematics.

The most notable passage, mathematically speaking, is when the protagonist decrypts in hours a file that would normally take years to a supercomputer, claiming to be using a technique for factoring large numbers he's discovered while amusing himself with number theory.

Your Help Needed: Some site visitors remember reading works of mathematical fiction that neither they nor I can identify. It is time to crowdsource this problem and ask for your help! You would help a neighbor find a missing pet...can't you also help a fellow site visitor find some missing works of mathematical fiction? Please take a look and let us know if you have seen these missing stories anywhere!.